According to the Department of Energy, 21 billion gallons of co-produced water are drawn up by oil and gas wells each year in the United States. Natural “oil” from a well is actually a multiphase fluid of oil/water/gas. Generally, all three fluids are found in every hydrocarbon well and well effluent.
Because of its value and because of environmental concerns, oil needs to be separated from this effluent. This is usually done through gravitational settling in large tanks, which requires capital and significant space that is not always available onsite. Gas is separated easily in a mechanical separator or by pressure reduction within storage containers. In the case of heavy oils and many emulsified fluid systems, the raw fluids are heated to change the density of the oil and water by heating off lighter ends and essentially agitating their molecular structures so that these fluids can more easily separate. Water then is a byproduct.
Filled microporous membranes are known to be low cost, efficient and environmentally friendly separation media for the separation of oil from byproduct water as mentioned above. Notwithstanding, as with most filtration media, over a period of time the filtration membranes can become fouled with residual oil and other contaminants. Such fouling can decrease the flux rates and, thus, reduce the efficiency of the filter devices. Hence, it would be desirable to provide a microporous membrane for use as an extended life filtration medium having improved anti-fouling properties while maintaining a high flux rate. The methods for treating filled microporous membranes as disclosed and claimed herein provide such improved anti-fouling properties.